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WOLF BLITZER, CNN ANCHOR: Right now, U.S. concern is growing over military exercises underway near the Ukrainian border. Is Russia getting ready to move forces in?

Also right now, newly released documents reveal more threats of retribution from Chris Christie's top aides. This time, they joke about punishing a rabbi by mysteriously delaying flights to Tel Aviv.

And right now, the inside story, we're learning new details about the massive effort to fix HealthCare.gov after the Web site's very rocky rollout.

Hello, I'm Wolf Blitzer reporting from Washington. We start with dramatic new developments in Ukraine. A group of armed men have now taken over the key government building in the regional capital of Crimea and they've raised the Russian flag. This is raising fears that Russia may step into the divide and into Ukraine.

Let's go to our Pentagon Correspondent Barbara Starr. Right now, Barbara, Russian forces are active along the border with Ukraine. Is there real serious fear Russia could potentially cross the line into Ukraine?

BARBARA STARR, CNN PENTAGON CORRESPONDENT: Well, Wolf, let's get right to defense secretary Chuck Hagel because there is an extraordinary optic out there. Earlier today at NATO headquarters in Brussels, secretary Hagel issued a warning to Moscow. And how many years has it been since a U.S. defense secretary had to do that? I want you to listen to what he had to say.

(BEGIN VIDEO CLIP)

CHUCK HAGEL, DEFENSE SECRETARY: I'm closely watching Russia's military exercises along the Ukrainian border, which they announced, as you know, yesterday. I expect Russia to be transparent about these activities. And I urged them not to take any steps that could be misinterpreted or lead to miscalculation during a very delicate time, a time of great tension.

(END VIDEO CLIP)

STARR: A direct warning from the U.S. to the Russian military. So, what is going on along that border? Well, Russian forces now on alert, conducting those exercises. The big worry, Wolf, is as they move closer to that border with Ukraine, as they move around and exercise and train, if that is indeed what they are doing, they get closer to the border if, if they were to get orders to move into Ukraine. They are that much closer, they could move very quickly, U.S. officials say, and it might be hard for U.S. intelligence to catch the first glimpse, the first information that they were on the move. The U.S. wants them to stay put. And they want plenty of time to engage in very, very assertive diplomacy with Moscow to make sure there are no moves -- Wolf.

BLITZER: And you can underline the urgency. You saw Chuck Hagel, the defense secretary, reading those carefully crafted remarks. Those weren't off the cuff or anything. That was a deliberately approved statement that he was issuing to Moscow.

So, what are the contingency plans? Are there contingency plans? Let's say Russians do move troops into Ukraine, what happens?

STARR: Well, you know, the question is, what would that look like? If there's 150,000 Russian troops moving across the border in a massive movement, which the U.S. does not expect, I must say, they have no belief that that's going to happen, that really becomes a massive worldwide crisis. Not just a security crisis, but an economic crisis for the region. You could see investment and that sort of thing dry up very fast with that kind of instability.

The big thing for (ph) the U.S., we're told, what if you get small units of Russian troops, small incursions across the border to very select places? What if in Sebastopol, the Black Sea fleet headquarters from Moscow? Things just become a little more uncertain. This drip, drip, drip of instability.

The U.S., right now, we are told, has no real option other than diplomacy and to use other countries also to convince Moscow and convince the emerging government in Ukraine not to engage in any destabilizing moves, not to take any steps that they can't move back from -- Wolf.

BLITZER: Let's see if the U.S. or the Europeans call for an urgent meeting of the United Nations Security Council. That would be an immediate first step if they sense something was about to happen. All right, Barbara, thanks very much. This map illustrates the divide in Ukraine. On the left, the western side of the country, people mostly speak Ukrainian. On the eastern side closest to Russia, they mostly speak Russian. Kiev, as you know, is the capital. And there, today, the parliament has chosen a new prime minister to lead what's called the interim government. Meanwhile, we know -- we now know a little bit more about the whereabouts of the former president, Victor Yanukovych.

Here's CNN's Phil Black in Kiev.

PHIL BLACK, CNN CORRESPONDENT: Russian state media had reported (INAUDIBLE) President Victor Yanukovych, a man who is now a fugitive in his own country, had requested personal protection from the Russian government and the Russian government had granted that protection on the territory of the Russian federation.

Now, Russian media is saying that Victor Yanukovych will hold a press conference in Russia in the southern city of Rostov-on-Don Friday.

Meanwhile, in the Ukrainian region of Crimea where pro-Russian government have taken over, that region's local parliament, local members of that parliament, have been voting, mostly to dismiss the local political administration. And secondly, calling for a referendum to determine if Crimea should become an independent sovereign state. It is a separatist question and one that the Crimea will now apparently vote for on May 25th, the same day the nation of Ukraine is scheduled to vote for its next president.

Phil Black, CNN, Kiev.

BLITZER: Other international news we're following, an interesting new attraction in Havana's Harbor. This Russian naval ship, it's a well- armed communications and surveillance ship complete with missiles. Usually arrivals like these are highly publicized in Cuba, but this -- but this one has been kept very low key. No one is talking about why this Russian ship is in Cuba right now.

North Korea flexing its muscles today by firing four, yes, four short- range missiles from a site near the border with South Korea. The missiles went into the Sea of Japan, also known as the east sea. The missiles can travel around 120 miles which would easily reach deep into South Korea. The timing is key here as the United States and South Korea just started their own joint military exercises earlier this week.

The North Korea's test launch is just one of several foreign policy issues President Obama's trying to juggle right now. We just touched on Russia, then there's the Syria civil war, nuclear talks with Iran, reports China is beefing up its Pacific fleet. And, of course, Afghanistan and the status of U.S. troops in that country.

Let's bring in our Chief International Correspondent, the anchor of Amanpour on CNN International, Christiane Amanpour. Christiane, let's start with Russia, and the feelings that potentially -- some are concerned we might be on the eve of another cold war. You've talked about the treaty that forbids Russia from getting involved in Ukraine. So, what, if anything, would stop Vladimir Putin from getting involved?

CHRISTIANE AMANPOUR, CNN CHIEF INTERNATIONAL CORRESPONDENT: Well, there doesn't seem to be any notion that he is actually going to do so, though just like secretary Hagel, the secretary general of NATO. Rasmussen also today tweeted a very similar warning to Russia talking about trying to take every step not to have any miscalculation, warning Russia not to do anything that could be misperceived. The new interim authorities in Ukraine have also called in the Russian (INAUDIBLE) in Kiev and they have issued him a demaje (ph) about what's going on as well.

And, interestingly, in the information that Barbara Starr had, the U.S., right now says it only sees Russia's military exercises, quote, "within their normal range." It does not see any of the kind of massive planning that Russia would have to do, in terms of planning and logistics and securing air and land and rail and road corridors, to incur into Ukraine.

And, of course, the Russians are saying they will not intervene militarily. Where does this leave everybody? Still a very tense crisis in the Ukraine. And what we're hearing from people who have been actually mediating, and certainly were at the beginning of this crisis, the number one, Russia, along with the U.S. and the U.K., does have a treaty not to interfere, basically respecting Ukraine's borders and its independence.

And also, the interim government is being urged to reach out to the ethnically Russian parts of Ukraine and to make sure that the new Ukraine is one for all Ukrainians, including those who have Russian ethnicity, including those in the Crimea.

So, yes, it's very tense right now but a lot of intensive diplomacy taking place along those lines to try to make sure it remains stable and this crisis doesn't spill out of control.

BLITZER: And when you think about it, Christiane, Ukraine, a very tense situation; as you correctly point out, North Korea, missiles being launched; China, the situation with Iran; Afghanistan, will U.S. troops stay there next year? All of these are huge, huge headaches, problems for the president of the United States. Which will you rank as the most serious right now?

AMANPOUR: Well, their big problems that -- and, of course, we're talking about an administration who does not want to intervene and is, in fact, pulling back from all sorts of engagements. And you mentioned Afghanistan. I just spoke to the former Afghan foreign minister, Zalmay Rasul, who is one of the main contenders for the presidential elections to succeed Hamid Karzai. And he said that it is time to repair relations with the United States, basically referring -- although not directly taking a dig at his former boss, but, basically, you know, that relations -- personal relations between President Obama and President Karzai are very poisoned.

The whole idea of President Karzai refusing to sign onto a security arrangement that would leave a U.S. residual force. All the other presidential candidates in Afghanistan want that residual force. All say that they would sign such an agreement should either one of them be elected. The majority of the Afghan people want that residual force of U.S., you know, personnel to stay beyond the 2014 withdrawal date.

So, most people think it's going to happen, but it's again, very much on a knife edge. And if there is no residual force, then begs the question, could Afghanistan turn into what Iraq is today? Incredibly violent, incredibly unstable with civil war, you know, festering there since U.S. pulled out all its troops couple of years ago.

The other more positive thing, perhaps counterintuitively, that's going on is the diplomacy between Iran and the United States and the other nations involved. By all accounts, that still is moving to try to, you know, restrict and restrain Iran's nuclear program in return for those eventual sanctions relief and bigger deal in the future. That seems to be progressing in the way that all sides have launched it right now. We'll see how that ends up as the talks get, you know, broader and deeper and more and more complicated.

BLITZER: Yes, and what's so depressing to me and so many others, Christiane, is that after 13 years of the United States deeply involved in Afghanistan, deploying 150,000 troops at one point, spending hundreds of billion dollars -- billions of dollars building up an Afghan military and police force. You are absolutely right. Without the U.S. there, they would crumble. Basically, it would deteriorate into a civil war. And it's a disaster, that situation. Three hundred thousand Afghan troops unable to get the job done. It's pretty depressing. Hamid Karzai's legacy a disaster. There's no doubt about that.

Christiane Amanpour, as usual, thanks very much.

Officials in New Jersey are releasing more texts between two key figures in what's called that bridgegate scandal. You're going to hear what one of Governor Chris Christie's top aides joked about with a port authority appointee. That's coming up next.

Later, Hillary Clinton's stepping into the spotlight in a politically critical state. You're going to find out about her comments in Florida and why they're making news today.

(COMMERCIAL BREAK)

BLITZER: You're looking at live pictures from the State Department. You see the German flag, the U.S. flag. The secretary of state, John Kerry, is going to be making a statement, together with the visiting foreign minister of Germany, Dr. Frank-Walter Steinmeier. Presumably they'll be speaking about what's going on in Ukraine right now and serious fears here in the United States, potentially. Let's hope it doesn't happen. The Russians could intervene militarily in their neighboring country of Ukraine. We'll monitor what the secretary of state, the German foreign minister have to say once they start speaking. Standby, we'll go to the State Department.

In the meantime, let's check some other news we're monitoring. The attorney general, Eric Holder, he's in a Washington, D.C. hospital right now. He was taken there earlier today after feeling faint. He also had shortness of breath. Moments ago, the White House press secretary, Jay Carney, talked about Holder's health in the White House briefing.

(BEGIN VIDEO CLIP)

UNIDENTIFIED MALE: You got anything to say about the attorney general being hospitalized? Has the president been made aware?

JAY CARNEY, WHITE HOUSE PRESS SECRETARY: The president has been made aware. And I think the Department of Justice has put out a statement that as a precaution when he felt faint earlier today, he was taken to Washington MedStar Hospital Center to undergo further evaluation. And he is resting comfortably and in good condition. He is alert and conversing with his doctors. The president was notified and, of course, wishes him a speedy recovery.

So, what else do we know about the attorney general's condition, Evan?

EVAN PEREZ, CNN JUSTICE REPORTER: Well, Wolf, he was in his normal morning meeting at 9:30 this morning with some of his top staff when he complain about feeling faint and shortness of breath. He excused himself from the meeting, went next door to his regular office and that's when his FBI security detail insisted that he go to the hospital. They called an ambulance. He was taken by ambulance to Washington -- MedStar Washington Hospital.

I'm told by someone who was there that he was joking with some of the EMTs as he was being rushed to the hospital and he is now in the hospital. He's resting comfortably. He's joking, talking to his doctors. So it appears whatever it was, he's now in good shape. Right now we don't know exactly what caused this, just that, you know, he complained of some faintness and some shortness of breath.

BLITZER: And he generally was regarded as in pretty good condition, not overweight, tall and seemed to be just fine. So let's hope it's nothing serious. And you'll continue to monitor it for us.

PEREZ: Sure.

BLITZER: Update us, Evan, when you get some more information. Let's hope he's out of that hospital fairly soon.

Meanwhile, there's other news, including some new information that's now surfacing about the New Jersey so-called Bridgegate scandal. Documents have just been released revealing conversations between a former top aide to the governor of New Jersey, Chris Christie, and the Port Authority official who ordered those notorious lane closures over at the George Washington Bridge. Our investigative correspondent Chris Frates has been looking over these new documents just released.

What are you seeing?

CHRIS FRATES, CNN INVESTIGATIVE CORRESPONDENT: Well, Wolf, I'll tell you, the new information, it comes from documents that we've seen before, but that had been previously blacked out. Now, today, the committee investigating Bridgegate said some of the information should not have been redacted. So they released new versions of both text messages and e-mails between a number of key players.

And the most interesting exchange involves a discussion between Bridget Kelly, now she was the former top Christie aide who has since been fired by the governor, and David Wildstein, who Christie appointed to the Port Authority. Now, in these texts, they joke about, of all things, causing traffic problems. Now, Wildstein sends Kelly a picture of a rabbi and says, quote, "he has officially pissed me off." She replies, "clearly. Can't we cause traffic problems in front of his house, can we?" And he jokes, "flights to Tel Aviv all mysteriously delayed."

Now, the rabbi, a gentleman by the name of Mendy Carlebach (ph), is chaplain of the Port Authority Police. It's not clear from the texts why Wildstein was so annoyed by him. So we reached out to the rabbi, but we haven't heard back yet.

There's also a separate exchange that's interesting. It's between Wildstein and a Port Authority police officer. And that shows us that Wildstein was on the bridge the first day of those lane closings.

BLITZER: Any other telling details released in these new documents?

FRATES: Well, I'll tell you, Wolf, there was a top Christie appointee to the Port Authority, Bill Baroni, and we see that he texts Wildstein at one point and asks, are we being fired? And that came about a month before he resigned. So we're still going through all these documents and we'll have a full report for you on "The Situation Room" a little bit later today.

BLITZER: Yes, 5:00 p.m. Eastern. And the fact that they're joking about, you know, traffic problems to Tel Aviv, obviously, you know, not good -- not looking good for these two - these two fired -

FRATES: It is not positive.

BLITZER: Yes, not good at all. All right, thanks very much, Chris Frates.

Up next, Hillary Clinton's trip to Florida fueling new speculation about her political future. Did she drop any hints about another run to the White House?

And later, a look back at the frantic effort to revive Obamacare. "Time" magazine takes a special behind the scenes look at the disastrous rollout of the website. We'll speak with the reporter who broke this story.

(COMMERCIAL BREAK)

BLITZER: Arizona Governor Jan Brewer's getting a lot of feedback on her decision to veto a controversial bill that opponents called anti- gay. The measure would have allowed businesses to refuse service to gay and lesbian customers if they felt it violated their religious beliefs. Senator John McCain tweeted, quote, "I appreciate Governor Brewer's decision to veto the bill. Everyone is welcome to enjoy our beautiful state of Arizona." Several conservative groups in the state criticized the veto saying the bill was about religious freedom not bigotry. Here's Brewer explaining her decision.

(BEGIN VIDEO CLIP) GOV. JAN BREWER (R), ARIZONA: I have not heard of one example in Arizona where business owners' religious liberty has been violated. The bill is broadly worded and could result in unintended and negative consequences.

(END VIDEO CLIP)

BLITZER: Hillary Clinton wasted little time applauding the veto of the Arizona bill. She commented on the decision during a speech at the University of Miami.

(BEGIN VIDEO CLIP)

HILLARY CLINTON, FORMER SECRETARY OF STATE: Thankfully, the governor of Arizona has vetoed the discriminatory legislation that was passed, recognizing that inclusive leadership is really what the 21st century is all about.

(END VIDEO CLIP)

BLITZER: Dana Bash is joining us right now.

She also touched upon the Affordable Care Act. What did she say about Obamacare?

DANA BASH, CNN CHIEF CONGRESSIONAL CORRESPONDENT: This is really fascinating. The only reason we know about this is because our colleague, Dan Merica (ph), went down and he figured out that he could actually go in and listen to what she was saying in what was thought to be a closed event. But it wasn't. And so what he heard her say was that she was actually open to some changes to Obamacare, specifically some of the things that we've heard from the president, but more importantly from Republicans, like the idea that businesses that have 50 or more employees, that those are the ones who have to offer health care. Concerned that people aren't just -- businesses aren't hiring to keep below that threshold. Maybe that should be changed. And then the other is the concept of the 30-hour marker as a part-time versus full- time, that maybe that needs to be addressed because, again, businesses are cutting back on workers hours to avoid having to bear the burden of Obamacare.

So those are the things that she talked about. Very noteworthy, I think, because those are also things that some of those who are also facing voters this year, some Democratic senators, are discussing. But she really did, according to Dan, who listened to her speech, back the whole concept of Obamacare because she said that you can't, in her words, throw the baby out with the bath because there are so many good things in it, like, for example, preventive care, the young invincibles, you know, those who are 26 and so forth making sure that they have health care.

BLITZER: How can it be a closed event at the University of Miami when there are hundreds of students there -

BASH: This is a -

BLITZER: TV cameras inside. What does that mean, a closed event?

BASH: It's a different event. She had a couple of events in Florida yesterday. One was open with TV cameras. This was earlier in the day in Orlando, Florida. It was a - it was meeting. Sort of a -- an event with health care I.T. people, which she was invited to. A lot of sort of technical people. A lot of sort of, as Dan put it, big brains in the room. That was --

BLITZER: It was separate, not at the University of Miami.

BASH: A separate event. A separate event, yes.

BLITZER: Because to have a closed event at the University of Miami did not make any sense.

BASH: Yes. No. And that's not where she talked about the Obamacare problems (ph).

BLITZER: She did -- at the University of Miami, she did have some fun talking about -

BASH: Yes.

BLITZER: Her Twitter feed, the way she describes herself on that Twitter page. And she specifically was asked about that TBD, to be determined, element that she mentions.

BASH: That's right. And I think we have it.

BLITZER: Let's watch this.

(BEGIN VIDEO CLIP)

HILLARY CLINTON, FORMER SECRETARY OF STATE: Well, I'd really like to, but I have no characters left. I will certainly ponder that.

(END VIDEO CLIP)

BLITZER: TBD, to be determined. She was talking about characters, 140 characters in a tweet.

BASH: Right. She was trying to have a little fun with the fact that she doesn't have any room. But I just -- to continue having a little fun with what she does have on her Twitter profile, check this out, I think we have it to put up. I mean, look at it. She - there's virtually nothing that she doesn't have. Wife, mom, lawyer, mom, women and kids advocate, FFLAR (ph) -- do you know what FFLAR is?

BLITZER: Floor?

BASH: Former first lady of Arkansas.

BLITZER: Oh, FFLAR - oh really?

BASH: It took me a while to figure that one out too. FLOTUS, so on and so forth. So she has everything in the world on there. TBD is obviously supposed to be a teaser and she continued with that at this event.

But by all accounts, just in watching what was that open event with the kids at University of Miami, with her old friend, Donna Shalala, who is the president of that university, she seemed to be creating the outlines of what could be a stump speech, talking a lot about the need to get involved, really appealing to the young people there, talking about her experiences when she was young, about listening to and watching MLK speak. And so certainly she's not -- she's teasing everybody, but she also seems to be honing what she might want to say if and when she does run for president.

BLITZER: Since she's been FLOTUS, first lady of the United States, maybe the TBD is she'd like to be POTUS, president of the United States.

BASH: We'll know - we'll find out.

BLITZER: We'll know fairly soon.

BASH: You know what, it's TBD.

BASH: Whether she -- and whether she gets to be POTUS is another matter. Whether she wants to be POTUS, I suspect she would like to be POTUS. All right, Dana, thanks very much.

BASH: Thanks, Wolf.

BLITZER: The incredibly rocky rollout of Obamacare. There's now some new behind-the-scenes information about how it all played out, what top officials knew and didn't know, and President Obama's backup plan. That's coming up next.

And take a look at this, a new White House push to help young men of color.